This invention relates to an aircraft and, more particularly, to a vertical lift aircraft employing a new and improved lift system.
Presently, helicopters are the most common vertical lift type aircrafts. The helicopters generally employ a single main rotor with a torque-compensating propeller on a boom at the rear of the helicopter. The body of the helicopter is located below the main rotor and is connected to the rotor system by a shaft which drives the rotor.
This conventional configuration has many deficiencies. For example, the rotor blades of the helicopter (generally between two and five) are long and heavy, and are connected to a single rotor hub; resulting in the rotor hub being heavily stressed. Damage to one of the rotor blades can create unbalances which can destroy the entire rotor system. Normal vibrations are also very difficult to damp in a conventional rotor system. The rotor blades, being free at one end, are easily damaged upon impact. The torque compensating propeller consumes a significant part of the engine power and adds a large amount of weight. The body of the helicopter being suspended below the rotor, interferes with the flow of air from the rotor, thus reducing the efficiency of the rotor. The rotor, being positioned high above the body of the helicopter, does not benefit fully from "ground effect", the lift-enhancing phenomena, which occurs when a lifting surface is operated close to the ground. The rotor of the helicopter operates at a much lower RPM than the engine which drives the rotor, necessitating the use of a heavy, RPM-reducing gear box. Other types of vertical lift aircrafts are shown in U.S. Pat. Nos. 3,437,290; 3,507,461; 3,514,053; 3,813,059 and 4,196,877. The above list is only exemplary and is not intended to be a complete list of vertical lift type aircrafts. In general, these patents address many of the deficiencies, noted above, of the helicopter type aircraft. In particular, these patents disclose the use of many airfoils located closer to the ground for providing lift as compared to the few rotor blades used on a helicopter. Further, the use of multiple sets of airfoils is disclosed in U.S. Pat. No. 3,813,059.